[#148] linter: Add funlen linter

Long functions are hard to understand and source of errors

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/frostfs-node/config.go

@@ -171,6 +171,8 @@ type subStorageCfg struct {
 
 // readConfig fills applicationConfiguration with raw configuration values
 // not modifying them.
+//
+// nolint: funlen
 func (a *applicationConfiguration) readConfig(c *config.Config) error {
 	if a._read {
 		err := c.Reload()
@@ -522,6 +524,7 @@ type cfgReputation struct {
 
 var persistateSideChainLastBlockKey = []byte("side_chain_last_processed_block")
 
+// nolint: funlen
 func initCfg(appCfg *config.Config) *cfg {
 	c := &cfg{}
 
@@ -654,6 +657,7 @@ type shardOptsWithID struct {
 	shOpts   []shard.Option
 }
 
+// nolint: funlen
 func (c *cfg) shardOpts() []shardOptsWithID {
 	shards := make([]shardOptsWithID, 0, len(c.EngineCfg.shards))